WARNING!: Working with electricity is dangerous, all information found on my site is for educational purpose and I accept no responsibility for others actions using the information found on this site.
Read this document about safety! http://www.pupman.com/safety.htm
Introduction
This is a modified version of the first SSTC I built, the Kaizer SSTC I. It uses the same secondary, topload and driver board. New things is a full bridge of IRFP460 MOSFETs, audio modulation, shielded drivers and a new casing.
Considerations
In the quest for longer sparks I decided to use a full bridge to take advantage of the full voltage on the bridge.
The MOSFETs will be mounted on top of a heatsink so its easy to change them by only removing the secondary platform and solder them off.
The drivers will be shielded in order to avoid the EM field generated by the Tesla coil itself to inject noise into the drivers.
Specifications
| Bridge | 4x IRFP460 MOSFETs in a full bridge configuration. |
| Bridge supply | 0 – 260 VAC from a variac, 8 A rectifier bridge and 1500 uF smoothing capacitor.0 – 365 VDC on the bridge. |
| Primary coil | 115 mm diameter, 1.78 mm diameter isolated copper wire, 8 windings. |
| Secondary coil | 110 mm diameter, 275 mm long, 1000 windings, 0.25 mm enamelled copper wire. |
| Resonant frequency | Selftuning at around 250 kHz. |
| Topload | 100 mm small diameter, 240 mm large diameter, toroid. |
| Input power | Continues Wave mode: 2000 – 4000 W at 200 VAC input voltage. Interrupted mode: 100 – 2000 W at 260 VAC input voltage. Audio modulated mode: 300 – 400 W at 150 VAC input voltage. |
| Spark length | up to 475 mm long sparks. |
Schematic
Construction
15th March 2009
I took apart a 19″ LCD monitor and a 24″ CRT monitor, from these respective computer parts I salvaged a good piece of plexi from the LCD monitor and a fairly sized heat sink from the CRT. I cut the plexi in half for a 2 level platform and the heat sink was cut in 4, its necessary to isolate the MOSFETs from each other as their housing is also a conductor.
19th March 2009
Driver electronics and audio modulator are installed under a metal casing from the CRT monitor to shield it from the heavy EM field surrounding the Tesla coil, this is to avoid problems with the driver being interrupted by its own EM field.
The bridge is made out of four IRFP460 MOSFETs, four MUR1560 diodes, four 5R resistors. The power supply is a 8A rectifier bridge with a BHC 1500 uF/450V smoothing capacitor, a 27K 7W bleeder resistor is added in the final build.
The audio in jack was later removed due to it making a short through its metal housing to the negative 12VDC rail, I had overlooked that the audio in negative was not common with the negative 12VDC rail.
The secondary is held in place by a crate for ventilation on houses, its an easy and quick way of taking the coil apart for transport or storage, and it holds the secondary firm and tight.
A plexi tube is added to support the antenna, in this way its possible to adjust the coupling of the antenna to the secondary simply by pulling the wire.
The new shielding of the audio in signal is made from a piece of shielding from a industrial cable pulled over it and grounded.
The complete coil looks, except maybe the electrical tape used to hold the topload together.
Sparks
Interrupted mode
At 250 VAC input voltage, 350 VDC on the bridge, it was possible to reach 475 mm long sparks, in interupted mode, to a grounded object.
More pictures of sparks in interrupted mode, it is running at about 4 – 5 BPS.
3rd May 2009
Continues Wave mode
At 200 VAC input voltage, 280 VDC on the bridge and a power consumption around 10A, peaking at 20A, the coil was drawing somewhere in between 2000 to 4000 Watt. This resulted in very hot, thick white arcs punishing the dead iPod shuffle which remarkably left the player relatively unharmed considered what had just taken place.
These flame like sparks are 250 mm in length.
Audio modulation
I use a audio modulator made by the user Reaching (Martin Ebbefeld) from 4hv.org.
For sound input I use a cheap children’s keyboard from a toy store, its far from perfect for the job, especially because its waveform is highly distorted and its not clean tones but seems to involve a lot of modulation inside it to simulate different instruments. But its cheap and expendable.
Watch the film and look at the schematics for more about the audio modulation.
Conclusion
Upgrading the SSTC I with a full bridge was a absolute must. It is small changes compared to the better performance and the driver have no problems at all driving four MOSFETs instead of just two.
Getting sparks at 475mm length in interrupted mode and white power arcs at 250mm length is truly satisfying for this little coil, the secondary winding itself is only 275mm in height in comparison.
Enjoy the demonstration.
what’s the amperage you are providing in your 12VDC interrupter and 9VDC modulator?
I use a 12VDC 2000mA wallwart supply, there is a 9V regulator for the modulator.
exuse me, but what is the value of your resistor on that cap
Ryan, what?
Please be more specific with your questions.
We would like to order SOLID STATE TESLA COIL for about 500 watt
please let us know if it possible and how much it will be
Regards,
Maxim Pryymuk
Skype: exclusiv-store
Ukraine
Why do you need two IRFP460′s? The second one really doesn’t do any thing! Would it not be closer to the 555 fly-back driver?
with a DC blocking capacitor.
Daniel R, you should read up on how a full bridge of transistors work, then you will understand why there is 4 IRFP460 MOSFETs.
f.ex. look at this short wikipedia article: http://en.wikipedia.org/wiki/H-bridge
I know how a full bridge works and I knew it takes four; I was talking about a half bridge, like the kaizer SSTC I. but useing a single Mosfet, I tryed it and it works just as good as two, ( but the Mosfet runs a little warmer).
It also works with a 555 timer circut, just not as easy to tune.
so I guess it really is like a fly back driver after all……… just self tuneing and w/ interupter.
induction heaters are just like tesla coils, Cool!
You are absolutely right, power electronics are to be found in almost any household item today, its just a question of the power levels
Electronics design really only comes down to one thing: Accepted component heating vs. production costs.
If we want better control, we have to pay more and the complexity of our designs raise too.
can your audio modulator work for DRSSTC, if only MIDI is played?
I am almost sure that Reaching from CTC-labs.de used it for his first DRSSTCs, but if you want a pure MIDI interface I would find something else
Hello, I’m Japanese high school students.
I want to make this sstc.
But I have some uncertain things.
So please answer two questions.
1.Does it work if IRFP460 is replaced with IRFP260?
2.How many Voltage is Rated Voltage Range of the C8 and C9?
I’m sorry my English is unskilled.
Hey Imai
1. IRFP260 will work at lower bus voltage, it is only rated for 200V where the IRFP460 is rated 500V, what is important is to keep a certain headroom, I would advise on atleast 30% headroom, so I would not apply more than 140VDC to a halfbridge of IRFP260.
2. The capacitors I used for C8/C9 are 400VAC MKP X2 capacitors, you can use any DC blocking low ESR capacitor as long as it has a higher voltage rating than your busvoltage.
I hope this help
Thank you for answering.
After all, I decided it to use of IRFP460.
Because it is more certain than IRFP260.
And I bought 400VAC capacitors.
Your advice helped me very much.
Thanks a lot!
Dear mads,
The capacitor in series with the + audio input, is it’s polarity shown correctly? negative side to the audio signal input (+) and positive side of the capactor to the 2K resistor?
Hey Erik
The capacitor is shown correctly, its a part of the filtering before the amplification in the op-amp.
Kind regards
Mads
Thank you for your help and your time mads.
Hi, Is there a way to run this SSTC from 250VAC in modulated mode?
If so, what modifications should I make?
Also I want to ask: If I use 12V (60A) instead of 350V for the primary, how many turns in the primary coil do I have to make?
I’ll use different mosfets of course…
Hi Jogosa
To run this coil at higher voltages you should decrease the primary to secondary coil coupling coefficient and of course insure that all components can withstand the higher voltage.
The thing is that with this topology you would need a very low primary impedance in order to get a current high enough with only 12 Volt through the primary, so a loose guess would be something half a turn…. If you want a low voltage Tesla coil I suggest you take a look at Skori’s Tesla coils: http://skory.gylcomp.hu/tesla-ml/index.htm
Kind regards
Mads
Thank you Mads. Already have both PCBs made, wondering whats the pulse width range on the timer…
By the way do you know an easy way how to make the topload?
Also as you said about decreasing coil coupling, did you meant putting the coils closer?
Will it be OK if I use 110mm diameter PVC pipe for the secondary and 160mm for the primary coil?
The coupling coefficient is a number representing the proximity of two coils, the lower the number the further the coils are from each other, at a coupling of 1 the two coils would occupy the same physical space, which is of course impossible in practise.
Read my article in order to see a easy to make topload.
The coupling for a SSTC will be too low with 30 mm between the coils, again look at my article.
OK, thanks for the help..
Hi again, Mads
I have already made and tested the driver circuit, and everything is working except that the transistor Q6 goes hot after a few seconds. Is that because it dissipates too much power when its switched on? Maybe I should use higher value for R14 ?
I tested it with 1kHz 900mV sine input the transistor gives me a square wave on the collector…
Hello,
I will be using the same components that you have listed but in North America we only have 120 VAC. What can I do to get the same HV output as your SSTC? ie increase the number of windings or increase the base frequency of the 555 timer?
Hello James
Increasing the number of windings on the secondary will only have a slight effect compared to higher bus voltage.
Increasing the bang per second rate of the interruptor will for a SSTC only result in thicker sparks, not much longer.
You should look up how to make a voltage doubler and add that to your circuit.
Kind regards
Mads
Hi Mads
What amplitude of audio input woltage should I give to get any effect for audio modulation? I have maked this, but after giving it about 0.5V audio signal(max) from mp3 player there are no signal from it. I have builded simmilar audio modulation for SSTC on TL494, but with same effect.
Sorry for my poor english.
Hey Radek
I used a toy keyboard with the volume at max, you might need a amplifier inbetween to get good results for a unamplified signal.
Kind regards
Mads
Hi good work very nice coil, My question is what is the diference between SSTC and DRSSTC? because I see to bridge LC system in the primary coil similar to used in DRSSTC? and when you used interrupter is very similar the sparks form, I will like make DRSSTC but I dont have IGBT do you think is possible used bridge of IRFP460 with low power? thanks.